Field of the Invention
The present invention relates to an organic compound having acetylene group(s), a thin film formed by vacuum deposition polymerization using said organic compound, vacuum deposition polymerization to form said thin film, and an electroluminescence device containing said thin film. More particularly, the present invention relates to an organic compound having at least one acetylene groups, vacuum deposition polymerization in which said organic compound is deposited on the substrate and simultaneously or then polymerized by thermal and/or UV radiation curing to form a polymer thin film, and an electroluminescence device using at least one layer of said thin film.
Organic functional thin film is recently used in Thin Film Transistor-Liquid Crystal Device (TFT-LCD), organic polymer electroluminescence devices, piezoelectric devices, optical materials and the like because it is applicable for portable electronics. Conventional organic thin film can be prepared by wet process such as dip coating or spin coating but it has disadvantages in that a certain polymer which is insoluble in a solvent requires an additional process of coating a precursor and heating to form a thin film. Further, wet process. results in problems including easy contamination by a solvent, difficulty in controlling film thickness and film uniformity below 100 nm. Also wet process is not favorable for a following process such as a manufacturing process of semiconductors which requires dry process.
On the other hand, a deposition polymerization is a method to produce an organic thin film by direct polymerization on the substrate by vaporizing a precursor with heat energy under high vacuum. Said deposition polymerization can i)produce a thin film through a simple vacuum device without using a catalyst or a solvent, ii)prevent from contamination of impurities, iii)control molecular sequences and film thickness, iv)provide easy preparing of a thin film of inprocessible polymer, and v)form a pattern by using a mask. Therefore, it is very important to develop thin film forming, technology by vacuum deposition polymerization which is expected to be essential to various electronic devices in future information industries.
There are two types of deposition polymerizations to form a thin film which are radical deposition polymerization and condensation polymerization. Radical deposition polymerization is a method to prepare a thin film on the substrate by polymerizing radicals generated by chemical reactions of precursors by thermal and/or UV radiation after vaporizing precursors. Different thin films such as poly(p-xylylene) (A. Greiner, Trends in Polymer 5(1997)7), 12), poly(naphthalene) (D. W. Smith et al., J. Am. Chem. Soc., 120(1998), 9078), poly(benzocyclobutene) or poly(p-phenylenevinylene) (K. M. Vaeth et al. Macromolecules, 31(1998), 6789), and Teflon (T. C. Nason et al., Appl. Phys. Lett. 60(1992), 1866), are prepared by radical deposition polymerization. Thin films prepared by said radical deposition polymerization provide excellent thermal stability and low dielectric constant and thus, they are very attractive for applications as interlayer dielectrics of semiconductors.
On the other hand, condensation polymerization is a method to prepare a thin film by condensation polymerization after two kinds of precursors are simultaneously deposited on the substrate. Thin films such as polyimide (Ukishima et al., Thin Solid Films, 308-309(1997), 479), polyamide (A. Kubono et. al., Thin Solid Films, 289(1996), 107), and polyurea (F. Fukuda, Key Eng. Mater., 92-93(1994), 143), polyazomethane (S. Tatsuura et al., Appl. Phys. Lett., 62(1993), 2182), are prepared by condensation polymerization. Thin films prepared by said condensation polymerization provide excellent electrical and optical properties such as piezoelectricity, non-linear optical property and conductivity and thus, they call the high attention as high-functional materials.
However, said radical deposition polymerization has to generate radicals by decomposing precursors at a high temperature over 400xc2x0 C. which is not suitable for the device manufacturing process. And said condensation polymerization has also disadvantages for producing by-products during condensation polymerization. Therefore, it is urgent to develop vacuum deposition polymerization which does not require thermal curing at a high temperature for decomposing precursors as well as does not produce by-products during polymerization and further, an appropriate precursor for vacuum deposition polymerization.
An object of the present invention is to provide an organic compound having at least one acetylene group which can be easily polymerized by thermal curing at relatively low temperature or UV irradiation.
Another object of the present invention is to provide a vacuum deposition polymerization to obtain a thin film having uniform thickness without generating by-products by using said organic compound.
Another object of the present invention is to provide a thin film prepared by vacuum deposition polymerization having an improved thermal stability.
Another object of the present invention is to provide an electroluminescent device fabricated by using said thin film.